docs: def gaussian_product_center(alpha1,A,alpha2,B):
      """
      The center of the Gaussian resulting from the product of two Gaussians:
      >>> gaussian_product_center(1,array((0,0,0),'d'),1,array((0,0,0),'d'))
      array([ 0.,  0.,  0.])
      """
      return (alpha1*A+alpha2*B)/(alpha1+alpha2)